One line of code makes your existing website usable by agentic AI browsers.

<script src="https://latch.tools/latch.js" defer></script>

AI browsers — ChatGPT Atlas, Perplexity Comet, Chrome 146+, Edge 147+ — can now operate web pages through WebMCP, the Web Model Context API (navigator.modelContext). But out of the box they have to guess at your buttons and forms, and they often fail. Latch reads your page (read-only) and exposes its core actions as WebMCP tools an agent can call directly.

No MCP server. No backend. No rebuild. Zero dependencies. ~6 KB.

Latch inspects the DOM and, when it finds them, registers:

If WebMCP isn't present in the browser, Latch does nothing — it never mutates or breaks the host page.

Drop the tag in before </body>:

<script src="https://latch.tools/latch.js" defer></script>

Or self-host: copy latch.js anywhere static and point the src at it.

Skip auto-init and drive it yourself:

<script src="/latch.js" data-latch-manual defer></script>
<script>
 // ...prepare your page, then:
 window.Latch.init();
</script>

Latch.inspect() returns what an agent would see — handy for debugging and the "agent's-eye view" on the landing page:

Latch.inspect();
// { webmcp: true, tools: [ { name: "search_site", why: "found a search input" }, ... ] }

Set Latch.debug = true before init for console diagnostics.

1. On DOMContentLoaded, Latch feature-detects navigator.modelContext (supporting both the registerTool() and provideContext({tools}) shapes).
2. It runs read-only DOM discovery to find your actionable surface.
3. It registers one WebMCP tool per capability, each with a JSON Schema an agent can reason about. execute() handlers dispatch native input/change events and requestSubmit() so your existing validation and handlers still run.
4. Failures are swallowed — the host page is never affected.

• Read-only discovery. Latch never scrapes content off-site, makes network calls, or sends data anywhere. It only registers tools the browser's own agent can choose to call, with the user in the loop.
• No backend, no keys, no cookies.

WebMCP shipped in Chrome 146 and Edge 147 (March 2026) and is implemented by agentic browsers (Atlas, Comet). Everywhere else, Latch is a no-op.

node --check latch.js # syntax check (the only "build")
python3 -m http.server # then open http://localhost:8000

MIT © Latch. See LICENSE.